The anionic block copolymerization of 4,4' -vinylphenyl-N,N-bis(4-tert-butylphenyl)benzenamine (A) with furfuryl isocyanate (B) was carried out using potassium naphthalenide (K-Naph) in tetrahydrofuran at -78 and -98 °C to prepare well-defined block copolymers containing furan groups for the formation of thermoreversible networks via a Diels Alder (DA) reaction. While no block copolymerization was observed in the absence of sodium tetraphenylborate (NaBPh 4) due to side reactions, well-defined poly-(B-b-A-b-B) (PBAB) copolymers with controlled molecular weights (M n = 18 700 19 500 g mol -1) and narrow molecular weight distributions (M w/M n = 1.08 -1.17) were successfully synthesized in the presence ofmore » excess NaBPh 4. We prevented the occurrence of the undesirable side reactions during polymerization of B of NaBPh 4, which results in the change in the countercation from K + to Na + for further polymerization of B. Moreover, the cross-linking via the DA reaction between the furan groups of PBAB and bismaleimide was proved by FT-IR and differential scanning calorimetry (DSC), and the thermoreversible properties of the cross-linked polymer were subsequently investigated using DSC and solubility testing.« less

Polymers that conduct protons in the hydrated state are of crucial importance in a wide variety of clean energy applications such as hydrogen fuel cells and artificial photosynthesis. Phosphonated and sulfonated polymers are known to conduct protons at low water content. In this study, we report on the synthesis phosphonated peptoid diblock copolymers, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), with volume fractions of pNpm (Φ Npm) values ranging from 0.13 to 0.44 and dispersity (¯D) ≤ 1.0003. The morphologies of the dry block copolypeptoids were determined by transmission electron microscopy and in both the dry and hydrated states by synchrotron small-angle X-ray scattering. Drymore » samples with Φ Npm > 0.13 exhibited a lamellar morphology. Upon hydration, the lowest molecular weight sample transitioned to a hexagonally packed cylinder morphology, while the others maintained their dry morphologies. Water uptake of all of the ordered samples was 8.1 ± 1.1 water molecules per phosphonate group. In spite of this, the proton conductivity of the ordered pNeh-b-pNpm copolymers ranged from 0.002 to 0.008 S/cm. Finally, we demonstrate that proton conductivity is maximized in high molecular weight, symmetric pNeh-b-pNpm copolymers.« less